From 1ae250301466c950248de5b5681954013bad21f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=BD=D0=B0=D0=B1?= <nabijaczleweli@nabijaczleweli.xyz>
Date: Mon, 16 Jun 2025 21:52:10 +0200
Subject: [PATCH] custom_model: open-code QtCore.QAbstractItemModel.hasIndex()

The implementation is just
	bool QAbstractItemModel::hasIndex(int row, int column, const QModelIndex &parent) const
	{
	    if (row < 0 || column < 0)
	        return false;
	    return row < rowCount(parent) && column < columnCount(parent);
	}
and yet it features as the most prominent part of the profile,
encompassing up to 25% of refresh()

Open-coding it makes refresh() 40% faster. Measurements from between
after wallet.get_full_history() and return from refresh()

Before:
	1.8637257907539606
	1.8563996930606663
	1.7696567592211068
	1.8933695629239082

After:
	1.3133591176010668
	1.3686819169670343
	1.2470976510085166
	1.2455544411204755
---
 electrum/gui/qt/custom_model.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/electrum/gui/qt/custom_model.py b/electrum/gui/qt/custom_model.py
index 099e041b3..e9f9b05dc 100644
--- a/electrum/gui/qt/custom_model.py
+++ b/electrum/gui/qt/custom_model.py
@@ -62,12 +62,18 @@ class CustomModel(QtCore.QAbstractItemModel):
         parent.addChild(self, node)
 
     def index(self, row, column, _parent=None):
+        # Performance-critical function
+
         if not _parent or not _parent.isValid():
             parent = self._root
         else:
             parent = _parent.internalPointer()
 
-        if not QtCore.QAbstractItemModel.hasIndex(self, row, column, _parent):
+        # Open-coded
+        #   if not QtCore.QAbstractItemModel.hasIndex(self, row, column, _parent):
+        # the implementation is equivalent but it's in C++,
+        # so VM entries take up inordinate amounts of time (up to 25% of refresh()):
+        if row < 0 or column < 0 or row >= self.rowCount(_parent) or column >= self._columncount:
             return QtCore.QModelIndex()
 
         child = parent.child(row)